Removable pallet cap bar



Aug. 10, 1965 s. A. HUFFMAN ETAL 3,199,356

REMOVABLE PALLET GAP BAR Original Filed April 11. 1960 VE TORS, SAMUEL Av HUFFMAN,DECEASED 5 g 5 BY FRANCES B- HUFFMANADMINISTRATRIX,

KENNETH M. HALEY, KENNETH R. JUDKINS BY W A rroelvs United States Patent 3,l=9,855 REIVEQVABLE PALLET AP BAR Samuel A. Huffman, deceased, late of Tucson, Ariz., by

Frances Huffman, admin stratrix, Tucson, Ariz., and

Kenneth M. Haley and Kenneth R. Judkins, Silver Bay,

Minn, assignors to Reserve It ining Qompany, a corporation of Minnesota Continuation of application Ser. No. 21,588, Apr. 11,

1960. his application lane 23, 1964, Ser. No.

2 Qlaims. (Cl. 266-21) This is a continuation of our copending application Serial No. 21,508 filed April 11, 1960, and now abandoned, for Removable Pallet Cap Bar.

The invention relates to a novel and improved pallet structure for use in a travelling grate conveyor.

The invention can be used to excellent advantage in the induration, at elevated temperatures, of pellets formed from powdered ferrous metal ore concentrates, but can also be used in the well known ore sintering processes of the type using travelling grates.

Machines of the type above mentioned usually consist of a train of end-to-end pallets moving on the upper flight or track of a conveyor system, and returning in upside-down fashion on the lower track. The pallets are provided with a grate bar arrangement for carrying the material to be indurated, sintered, or otherwise subjected to elevated temperatures during at least a portion of the travel on the upper track.

The various heating and reaction steps are achieved by the use of streams of heated air, or in some processes actual flame jets impinge upon and pass through the load, and of course through spaces between the grate bars and between the supporting pallet frame members. The grate bars and pallet frames reach a high temperature in the furnace zone, and there are severe temperature gradients resulting from alternating heating and cooling steps.

The upper surfaces particularly of the pallet portions which directly contact and support the grate members or grate bars exhibit various injurious effects such as progressive cracking, warpage, and burn-off, this latter causing a gradual disintegration. All such eifects, after they reach a critical stage, render the pallet unfit for further use. A commonly used grate construction in cludes a plurality of individual grate bars, for easy replacement, but they are usually retained on the pallets by simple mechanical interlock (one such interlock being herein later described) and warpage or failure of the critical pallet frame portions results in droppage of grate bars, especially when the pallets turn to the upside-down position at the turnover point of the endless conveyor system. Material in the load will also drop between loosely fitting grate bars caused by pallet warpage.

As will later appear a pallet frame comprises a framework of plates, ribs, webs, etc., for the support of the grate structure, and one of the injurious effects encountered consists of differential heating between upper and lower surfaces of these members. This produces top surface cracks and these cracks gradually progress downwardly until a complete failure occurs under load. Burnoff is now also a major problem wherein the interconnecting lug and flange portions of grate bars and pallets crumble away to the point where the grate bars cannot be retained. Warpage of pallet frame members has the same eventual effect.

Attempts have heretofore been made to produce removable fractional portions of a pallet which would be replaceable after they were sutiiciently damaged, thereby saving the cost of a complete pallet frame replacement.

3,l9 ,856 Patented Aug. it 1%55 "ice Efforts along this line have been unsuccessful, mainly because the pallet frames still warped.

An object of the present invention is to produce a pallet structure which eliminates or greatly reduces warpage, burn-off, and cracking.

A further object of the invention is to provide replaceable pallet portions attachable in such a manner that they will maintain correct positional relationships with other pallet parts, so that the grate bars will remain in proper pre-set positions.

Other objects and advantages will become apparent from a study of the following description of one exemplification of the invention, in conjunction with the accompanying drawings, in which FIG. 1 is a top plan view of a travelling pallet, showing a few grate bars supported thereon.

FIG. 2 is a fragmentary sectional view, somewhat enlarged, taken on the line 2-2 of FIG. 1.

FIG, 3 is a sectional view, still further enlarged, taken on the line 3-3 of FIG. 2.

Proceeding now to a description of the present embodiment of the invention we show, in FIG. 1 a pallet frame movable on wheels 20 on a track 21. The pallet is split longitudinally on the plane designated by reference numeral 22, the two pallet parts 23a and 23b being held together by bolts 24. Such a split pallet structure is not claimed as novel herein, but it has been found helpful in the avoidance of manufacturing, assembly, and operational problems. Since the construction of both pallet halves is identical, they being symmetrical about the plane 22, further description will be confined to the pallet portion 23b.

Pallet part 231) is a rectangular hollow frame having side bars 25 and 26, front and rear end bars 27 and 2%, internal strengthening ribs 29 and 30, and transverse webs 31, 32, 33.

A closely fitted plurality of grate bars 36 are carried on the end bars and ribs and are retained therein in any readily removable way. The ribs, in the embodiment shown, are provided with iuturned flanges and the grate bars have depending brackets with outturned fingers or lugs which extend beneath the rib flanges so that the grate bar is retained when the pallet turns upside down so as to arrive on the lower track. FIG. 3 shows a grate bar 36 of this type having a depending bracket 37 with outturned lugs 38. The pallet ribs 29 and 30 have however been redesigned in a manner now to be described.

We have provided a protective pallet cap bar 39 which overlies the ribs 29 and 3t and extends inwardly beyond the ribs an amount sufiicient to provide a grate bar retaining portion 39a. Each of the ribs 29 and 3t) and its respective cap bar are provided with registering holes to receive connecting bolts 40. The attachment of the ribs and cap bars by means of horizontal bolts arranged in this way appears to greatly reduce warpage in contradistinction to the former vertical connecting means. It is also apparent that the right angled arrangement of the cap bar flanges presents a more or less warp-proof structure which imparts this useful characteristic to the vertical ribs 29, 30 by means of the horizontal attaching bolts. Also, the angular cross sectional contour of the cap bar provides a horizontal flange 39a which inwardly overhangs the rib 3t so as to provide additional protection from heat, and a vertical flange 39b which shields an upper side portion of rib 30.

The cap bars are exposed to direct contact with high temperatures and the metallic discontinuity between the cap bars and the top surfaces of ribs 29 and 3t greatly reduces or entirely eliminates incipient cracking or burnoif in the ribs. When the cap bars begin to crack or disintegrate they may be readily replaced by new ones, thereby effecting substantial savings in pallet'costs.

What is claimed is:

1. Protective means for a pallet of the character described wherein said pallet includes a hollow frame and a transverse rib extending between opposite sides of the frame and adapted to support a grate bar structure, said rib having a flat upper surface and a flat side face depending substantially at right angles to said upper surface, said protective means comprising a cap bar having two integral flanges at right angles to each other consisting of a top flange in planar surface contact with the flat upper surface of said rib and with its free edge extending beyond said flat side face to provide a protruding flange projection for complementary cooperation with a grate bar retaining lug, and said cap bar having a second flange depending downwardly in planar contact with said flat side face of said rib, said rib and said second flange having aligned apertures to receive retaining means extending horizontally therethrough whereby to reduce warpage of said cap bar.

2. Protective means for a pallet of the character described wherein said pallet includes a hollow frame and a pair of spaced parallel transverse ribs extending between opposite sides of the frame, and adapted to support a grate bar assembly, each said rib having a flat upper surface and a flat side face depending substantially at right angles to its said upper surface, said protective means comprising respective cap bars, one for each rib, each said cap bar having two integral flanges at right angles to each other consisting of a top flange in planar surface contact with the flat upper surface of said rib and with its free edge extending beyond said flat side face towards the other rib to provide a protruding flange projection for complementary cooperation with a grate bar retaining lug, and each said cap bar having a second flange depending downwardly in planar contact with said flat side face of its respective rib, each said rib and the respective depending flange in contact therewith having aligned apertures to receive retaining means extending horizontally therethrough whereby to reduce warpage of said cap bars.

References Cited by the Examiner UNITED STATES PATENTS 1,388,335 8/21 Greenawalt 266-21 1,889,052 11/32 Najarian 26621 MORRIS O. WOLK, Primary Examiner. 

1. PROTECTIVE MEANS FOR A PALLET OF THE CHARACTER DESCRIBED WHEREIN SAID PALLET INCLUDES A HOLLOW FRAME AND A TRANSVERSE RIB EXTENDING BETWEEN OPPOSITE SIDES OF THE FRAME AND ADAPTED TO SUPPORT A GRATE BAR STRUCTURE, SAID RIB HAVING A FLAT UPPER SURFACE AND A FLAT SIDE FACE DEPENDING SUBSTANTIALLY AT RIGHT ANGLES TO SAID UPPER SURFACE, SAID PROTECTIVE MEANS COMPRISING A CAP BAR HAVING TOW INTEGRAL FLANGES AT RIGHT ANGLES TO EACH OTHER CONSISTING OF A TOP FLANGE IN PLANAR SURFACE CONTACT WITH THE FLAT UPPER SURFACE OF SAID RIB AND WEITH ITS FREE EDGE EXTENDING BEYOND SAID FLAT SIDE FACE TO PROVIDE A PROTRUDING FLANGE PROJECTION FOR COMPLEMENTARY COOEPERATION WITH A GRATE BAR RETAINING LUG, AND SAID CAP BAR HAVING A SECOND FLANGE DEPENDING DOWNWARDLY IN PLANAR CONTACT WITH SAID FLAT SIDE FACE OF SAID RIB, SAID RIB AND SAID SECOND FLANGE HAVING ALIGNEDX APERTURES TO RECEIVE RETAINING MEANS EXTENDING HORIZONTALLY THERETHROUGH WHEREBY TO REDUCE WARPAGE OF SAID CAP BAR. 